Guwahati: A rare Himalayan toad has revealed its long-hidden breeding secrets, with scientists documenting its first-known egg mass and highest-altitude record in Arunachal Pradesh.
The discovery was made in the Dibang River Basin of eastern Arunachal Pradesh, where researchers recorded amplexus (mating behaviour) and an egg mass containing around 110–130 eggs of the Bompu Litter Toad (Leptobrachium bompu) a species whose reproductive biology had remained unknown since it was first described in 2011.
The findings, published in the journal Reptiles & Amphibians, are based on field surveys conducted in May 2018. Researchers first encountered calling individuals near Mehao Lake in Lower Dibang Valley at an elevation of 1,698 metres.
A subsequent survey near Mayodia Pass led to the discovery of a breeding population along a slow-flowing mountain stream at 2,510 metres above sea level, marking the highest elevation record for the species in India and Bhutan.
At the Mayodia Pass site, male toads were observed calling from gaps between boulders, while researchers documented amplexus and found an egg mass attached to a streamside boulder, encased in gelatinous sheaths.
This marks the first confirmed observation of egg-laying in Leptobrachium bompu anywhere in its known range.
The Bompu Litter Toad is currently listed as ‘Least Concern’ on the IUCN Red List and is known from limited locations in Arunachal Pradesh, Bhutan, and parts of Tibet in China.
Apart from its type locality in Eaglenest Wildlife Sanctuary, the species has previously been recorded in Talle Valley Wildlife Sanctuary, Lower Subansiri district, Bhutan’s Sarpang district, and Upper Medog in Tibet.
Researchers note that despite its conservation status, the species remains poorly studied, and the lack of information on its breeding ecology has limited understanding of its habitat needs.
The new findings provide crucial baseline data, particularly as high-altitude stream ecosystems face growing pressures from climate change, road expansion, and human activity.
Photographic vouchers from both sites have been deposited at the Lee Kong Chian Natural History Museum at the National University of Singapore.
The species identification was confirmed by noted herpetologist Sushil Kumar Dutta, retired professor at North Orissa University.
The study was authored by Jayanta Kr. Roy, M. Firoz Ahmed, Regon Menda, and Ramie H. Begum, representing research institutions in Assam and Arunachal Pradesh, and underscores the Dibang landscape’s emerging importance as a hotspot for undocumented Himalayan biodiversity.